Tropical Storm Alex's Yucatan Landfall

This Animated loop shows the development of Alex's eye. The page for Belize's radar is here.

The 500AM EDT forecast is a bit different than the previous forecast. Essentially, it looks like the area of high pressure in the northern Gulf of Mexico will weaken due to a trough over the eastern US. This will weaken the steering currents and slow's Alex's motion over the Gulf of Mexico. The reduced storm motion will give Alex more time to intensify in a a warm SST/weak shear environment. The current forecast calls for Alex to become a category 2 storm before making landfall north of Tampico, MX late Wed. night/early Thursday morning.

The $64,000 question is "Will the ridge continue to weaken, allowing Alex to move north and continue intensification?" The 12Z global model runs will have more accurate forecasts than the the 6Z runs thanks to the presence of radiosonde data, so hopefully they'll provide an answer. It's still my opinion that Alex will not directly impact the oil spill recovery efforts, but I can't say that the chances of it doing so are getting smaller now.

This is Dr. Rob Carver, filling in for Jeff during the late shift. Tropical Storm Alex is currently moving over the Yucatan peninsula. Alex's intensity has dropped to 50 knots in the latest advisory with further weakening expected as the storm moves over land. After Alex moves into the Gulf of Mexico, intensification is expected because of warm sea-surface temperatures and weak vertical wind shear. An area of high pressure in the northern Gulf of Mexico will guide Alex into a WNW-NW track. The 200AM EDT forecast calls for Alex to intensify into a category 1 hurricane before making landfall just north of Tampico, MX.

In my judgement, the chances of Alex moving northwards and directly interfering with the Deepwater Horizon oil spill recovery efforts are small and getting smaller with time. I agree with Jeff's assessment that Alex will generate 2+ foot swells that would interfere with skimming operations

Currently, the main threat from Alex is flooding due to heavy rains. NHC is forecasting rainfall amounts from 4 to 8 inches with higher amounts over mountainous terrain, causing flooding and possibly mudslides.

There isn't much storm structure apparent in the reflectivity data, just widespread areas of showers. Data from a nearby PWS shows that the peak windspeed was 43 mph. You can clearly see the circulation move past the station with changes in the wind direction and speed. You can also see when the rainbands passed over the station.

Invest 94LInvest 94L is still out there, but it's not looking healthy. It's currently in an area unfavorable for tropical cyclogenesis and NHC thinks it has a 0% chance of becoming a tropical storm in the next two days. Current forecast models have 94L moving northwards and making a pass by Bermuda.

If things don't change significantly, Jeff is thinking about taking Sunday off. However, rest assured that if Alex starts charging towards the US, Jeff or I will put up a new entry. In any event, I'm planning on posting an update sometime late Sunday evening.

TROPICAL WEATHER...TROPICAL STORM ALEX IS FORECAST TO CONTINUE TO THE WEST NORTHWESTACROSS THE SOUTHERN GULF OF MEXICO AND INTO NORTHERN MEXICO LATERTHIS WEEK. AT THIS TIME THERE IS LESS THAN A 10 PERCENT CHANCE OFTROPICAL STORM FORCE WINDS AFFECTING THE SOUTHEAST TEXAS ANDSOUTHWEST LOUISIANA COAST OVER THE NEXT FIVE DAYS.

My concern is that the NHC is underestimating the type of intensification Alex could do with a few days over the Gulf of Mexico

It appears the strength of Alex is going to have a pretty big impact on how far north it goes; and an underestimation in its eventual strength likely will also mean that they are focusing the track too far south

Exactly. The NHC is waiting about 72-84 hours before Alex becomes a hurricane. With the current conditions that can be achieved in 36 hours.

My concern is that the NHC is underestimating the type of intensification Alex could do with a few days over the Gulf of Mexico

It appears the strength of Alex is going to have a pretty big impact on how far north it goes; and an underestimation in its eventual strength likely will also mean that they are focusing the track too far south

You can definitely see on MIMIC on the last couple of frames the storm was pushed due west, maybe even a tad bit south of due west, but on like the last frame it looks like it resumes it's previous WNW-NW movement.

Quoting louisianaboy444:Levi, Do you think if Alex intensifies quickly that the other models will latch on...what concerns me is the BAMD model takes it quite near the GFS model or it did last night...and that is the steering model for Deeper systems

And yet it's one of the most southerly outliers of the 12z model package this morning. Lots of flip-flopping going on with the BAM suite lately, illustrating the uncertainties. I'm not sure how well the intensity guidance will catch on if Alex deepens quickly, but the models will of course be initialized with Alex's initial intensity.

All those ensemble members show it going NW right now though, what I see on the Rainbow IR is just north of W. I'm confused lol.

Well they show WNW until Alex is back over water. Right now the long term motion has been WNW, but the short term as you mentioned is more westerly. As Pat mentioned, this might be due to some frictional effects, and whatever the cause, Alex should turn more towards the NW shortly, probably after exiting the coast.

Levi, Do you think if Alex intensifies quickly that the other models will latch on...what concerns me is the BAMD model takes it quite near the GFS model or it did last night...and that is the steering model for Deeper systems

Don't look for much in the way of new COCs forming. According to the NHC 10 am discussion "...the low-levelcirculation of Alex remains well defined..." I suspect the circulation is finally broadening a bit, though.

It's interesting...I'm used to seeing the circulation broaden in size and then the pressure rise, not the other way around, as Alex has done overnight.

The "regular" GFS is the operational model, which is one run, by one model, and is what we think of as "the GFS".

The GFS ensembles are different runs of the GFS with slightly different parameters, in order to try to cover all possible scenarios. The ensemble mean is not plotted on the TC track maps, but the ensemble members are and you can see where they are all going.

The GFS operational (white line) and its ensemble members are in outstanding agreement right now. One would never think that the other models are several hundred miles different. I don't think I've ever seen the GFS ensembles this confident in the face of this much disagreement from the model consensus.

All those ensemble members show it going NW right now though, what I see on the Rainbow IR is just north of W. I'm confused lol.

...MOISTURE/UPPER REMNANTS OF ALEX MAY BE DIRECTED NORTHWARDTHROUGH THE EASTERN PLAINS...

...PRELIMINARY UPDATE...

THE PRELIMINARY FRONTS AND PRESSURES FOR DAYS 3 THROUGH 7 WEREUPDATED USING THE 00Z ECENS MEAN...WITH THE TPC FORECAST FOR ALEXACROSS THE WESTERN GULF OF MEXICO. THIS MORNINGS GUIDANCE IS MORETIGHTLY CLUSTERED THAT YESTERDAYS WITH THE POLAR JET DURING THEMEDIUM RANGE...WITH THE ECENS MEAN...ECMWF...UKMET...AND CMCE MEANALL VERY CLOSE AND HONORING CONTINUITY BETTER THAN THE GFS ANDGEFS PRODUCTS. THE NEW DEVELOPMENT IS THE LARGE QUANTITY OFGUIDANCE THAT TAKES SOME ASPECT OF ALEX NORTHWARD THROUGH TEXASAND THE EASTERN GREAT PLAINS LATE IN THE PERIOD. THERE MAY NOT BEMUCH SURFACE REFLECTION...WITH THE GEM GLOBAL A LOW PROBABILITYOUTLIER...BUT ENOUGH MID LEVEL ENERGY AND DEEP LAYERED MOISTUREMAY BE ABLE TO TRACK UP THE WESTERN EDGE OF THE SUBTROPICALRIDGE...ON A GENTLE ARC FROM EASTERN TEXAS TO IOWA BY THE END OFDAY 7...TO THREATEN THIS SWATH OF TERRITORY WITH HEAVY RAINS. ADDITIONALLY...THE POLAR FRONT BOTTOMING OUT ALONG THE NORTHERNGULF COAST IS LIKELY TO AFFORD AN INTENSE OVERRUNNINGZONE...INTERCEPTING THE SURGE OF TROPICAL AIR WORKING UP THEBACKSIDE OF THE UPPER RIDGE. THE NORTHWEST SHOULD SEE A CONTINUEDINFLUX OF MARITIME POLAR AIR OFF THE PACIFIC...THOUGH RAINFALLSHOULD BE LIMITED BY MOSTLY CHANNELED VORTICITY.

Until I see a major change or trend in the models or Alex's movement, I will stick with my forecast from yesterday morning calling for a landfall in Mexico near 25N, which is currently to the north of the NHC and model consensus.

Oh ok, so the page with GFS ensembles is just GFS runs in every way possible and they combine it all to make the GFS model on the "reliable" model page..

The "regular" GFS is the operational model, which is one run, by one model, and is what we think of as "the GFS".

The GFS ensembles are different runs of the GFS with slightly different parameters, in order to try to cover all possible scenarios. The ensemble mean is not plotted on the TC track maps, but the ensemble members are and you can see where they are all going.

The GFS operational (white line) and its ensemble members are in outstanding agreement right now. One would never think that the other models are several hundred miles different. I don't think I've ever seen the GFS ensembles this confident in the face of this much disagreement from the model consensus.